The present invention relates to a gas turbine combustor having a flow sleeve and a liner for supplying compressor discharge air to combustor burners and particularly relates to a casing for turning compressor discharge air flowing radially through holes in the flow sleeve in an axial direction for flow in a generally parallel direction relative to the free stream air in the flow sleeve. The invention also relates to methods for turning the flow.
In current combustors, a plurality of openings are provided about the flow sleeve for injecting air in a generally radial direction into the flow sleeve for impingement cooling the liner. The radially injected air is generally normal to the free stream air flowing within the flow sleeve. It will be appreciated that compressor discharge air flows through openings in the impingement sleeve of a transition piece and forms part of a free stream air flow in an aft direction and between the combustion flow sleeve and liner. This air flow mixes with fuel at the aft end of the combustor and the fuel/air mixture is combusted within the liner. The air injected in the radial direction through the flow sleeve openings and into the free stream has a momentum exchange with the axially flowing air and must be accelerated by the axially flowing free stream air until the cross flowing air reaches the free stream velocity. This process causes a net loss in energy.
In certain combustors, it is desirable to impingement cool the liner of the combustor, necessitating the net loss in energy to cool the liner. In other combustors, however, the magnitude of cooling required to cool the liner is such as to not require impingement cooling flows. Consequently, there is a need to provide a mechanism and a method for reducing energy losses due to cross flow while affording cooling of the liner.